kas, I noticed after you said that your alternator ground wire had its own ground point on the engine block. That should not be. It should go to one main ground point, actually its best to go to a grnd. bus near the battery. Also looking at your picture the alternator ground wire is much smaller than the positive cable. They should always be the same size. Perhaps Bavaria can help you with wiring diagrams. It looks like factory wiring but I am really surprised that Bavaria would wire up your system like that.

kas, I would do one thing at a time. First isolate your batteries with an ACR of your choosing, then inspect your wiring to see if it meets best practice and solve that situation. But as I said above, in a different way, your engine block should never be used as an electrical conductor.

DeepFrz, I have contacted Bavaria to try to get a detailed wiring diagram so I can trace the cables and label them myself (if nothing else) so hopefully they will come through soon. I agree it seemed odd to me to have a separate ground point for the alternator especially as it was so close to the point used by all the other ground cables. And you are correct the wiring is exactly as it came from the factory 5 years ago.

Hellosailor, not sure where you found the info on the cables but that's not what I found from the manufacturers website. The info I have states "annealed copper conductor, class 5 flexible, suitable for fixed installations up to 750v DC to earth". There are 3 versions; solid core, thick multi strand and thin multi strand. It is also flame retardant to IEC60332-1-2 and temperature rated from -30ºC to +70ºC. So it appears suitable for purpose and not something anyone cobbled together, which is as one would hope as it is factory fitted and subject to RCD and CE approvals.
As far as I can tell there are no diodes or other restrictions in the Alternator Sense lead. It runs directly to the anchorwindlass positive spur from the house battery cabling. This kind of makes sense as it will pick up the power drain when the windlass is in use thereby ensuring the alternator is providing power when needed. I have just checked the voltage at this point and it is reading 14.25v. The only thing I can think of at this point is that it is a long cable (approx 5m) so could there be a voltage drop due to that? Not easy to measure as the ends of the cable are too far apart for my multimeter.

I am in agreement with everyone that the components need to be charged for newer more efficient and effective items. I have committed myself to that fact. Once I have a detailed wiring diagram and can check the system is as it should be then I can move forward and get this changed out.

Just been browsing round the local marine shop and spot a Quick ECS 162 Electronic Charge Separator. Looking at the technical manual from the manufacturer it looks like this could be a contender to replace the diode isolator.

It offers "negligible loss of voltage", "low power dissipation" and "IG terminal for alternator excitation" amongst other features. It can handle alternator charge of up to 160 amps which is way more than the 115amps mine puts out and battery chargercurrent of 120amps. It is also the same make as my mains charger so there should be no conflicts there.

Has anyone had any experience of this particular model?

As it is here in country it would be a lot easier than having to pay shipping to get something from UK or further afield.

Think I may have made a breakthrough in determining the size of the various wires. After a fun filled day, sweating buckets (it's 35ºC here), with my head in various compartments I found several connectors with sizes marked on.

So the main set of wires leading from the Alternator to the isolator then onward to the Starter Motor and House battery (separate circuits) are fitted with connectors marked 8x50. These are the ones with the 40mm external circumference or 12.7mm OD.

The thicker wires leading from the Starter Motor to the Starter Battery are fitted with 10x95 connectors. These are the 54mm external circumference or 17.2mm OD.

The thinner wires that lead to the Thruster battery are marked on the insulation with 1x10. These are the 20mm external circumference or 6.4m OD ones.

I also discovered that the House battery cables are fitted with ?x120 connectors and these are big cables.

Ground wires are the same size as live with the exception of that odd one from the alternator direct to the block.

Does any of this make sense to the collective?

Additionally I fired up the lump this morning as part of my weekly engine checks so monitored the voltages to the various parts of the system.

The alternator was putting out a steady 15.25v with 15.20-15.25v at the diode connection. From the diode to the starter battery was a steady 14.8v (via the starter motor) and to the house battery a steady 14.2v. No fluctuations were observed and there was no reduction in the charge voltage at the alternator despite the house battery/alternator sense lead connection measuring 14.2v (as per multimeter), the house battery monitor was indicating a 1.5amp charge though.

Interestingly the voltage reading for the starter battery in my instrument panel was showing 15.2v so this makes me think the panel is getting the voltage from somewhere other than the actual starter battery, most likely the alternator direct but that makes zero sense even to a rock doctor like me.

Keiron

ps I switched off the mains supply before starting up the engine to remove any additional charge sources to all the batteries.

Keiron-
I found the (mis)information on Google. Bear in mind, Google generates different results in each geography, so "Google-US" and "Google-Greece" wouldn't be the same. European wiring specs probably are going to come up differently in the EU. And more accurately.

No idea about the gizmo you found, you might want to ask the maker just what it is and how it works. The charge combiners in the US fall into two main camps. The old design (Yandina/West) uses a relay to control power, the new designs use power transistors (FET) and take less idle current. Whether you think one or the other is more reliable, is somewhat of a personal choice. I think relays are "dumber" but transistors find their own clever ways to fail as well.

Hopefully Bavaria gets back to you in a couple of days.

Unlike Deepfrz, I've never seen an alternator with it's own ground wire. They "always" are grounded just by the alternator foot, which is firmly bolted to the engine block, which IS always used as the ground conductor for the alternator, at least in the usual sizes and car and boat engines. Save a buck on the wire and two more bucks on installing it, and soon enough you wind up saving five bucks on each engine for a ground wire that is totally useless and redundant for this type of installation. I'd bet that if you put a clamp ammeter on that ground wire, it would show "damn near zero" ohms during actual operation.

Hellosailor; and Google Croatia comes up in Hrvatskom unless you swap it to English I found the details I have from the manufacturers website at tfkable.com

I've been scratching my head about that odd ground wire as well. I did check it with the voltmeter this morning and it was showing the same as all the other circuits.

There are actually 2 black/ground wires coming from that terminal, which is the B post, but I have not been able to trace where the really small one goes as it disappears into a multitude of wires all held in sheathing.

Here's hoping I can get the electrical engineer's wiring diagram soon or I'll be manually tracing wires

Most (all?) automotive type alternators have a grounded case. Many of the high output alternators have an isolated case and therefore need a ground cable the same capacity as the positive cable. In the picture posted above it looked like the negative connection was isolated but it may not be. The ground cable should still be a larger cable and it certainly isn't wired using best practices.

Tried a little experiment this morning to see if I could tell if the alternator/regulator are working properly before I took said alternator off for testing.

I disconnected the sense wire, which is connected to the house/anchor windlass, and connected the regulator up to the starter battery instead.

Disconnected the mains power and shut down all the electrics so there were no drains on the system at all. Just the solar panels pumping a few amps into the house battery.

Fired up the lump and checked the voltages;
At the Alternator 14.5v
At the Starter Battery 14.2v
At the House Battery 14.2v (thruster showed 13.85v measured at the separate diode)

Leaving the engine running for a few minutes I monitored the voltage coming out from the alternator and it steadily dropped down from 14.5v to 14.25v. Fluctuated a little but no more than +/-0.5v I continued to monitor and the alternator kept producing a steady 14.25v.
I then shut down and swapped back to the original sense wire and tried again.

At the Alternator 14.5v
At the House Battery 14.25v (this was actually measured at the diode not the battery)
At the Starter Battery 14.25v
Again as I let the engine run and monitored the voltages the alternator slowly came down from 14.5v to 14.25v with both the batteries showing 14.2v (+/-0.5v). All steady with no spikes or fluctuations.

This means the regulator is doing it's job at the basic level at least so should mean I don't need to remove the alternator.

Doesn't get me any closer to finding out why we suddenly got the high voltages in June when this all started but at least I have removed a few variables.

So the plan now is thus:
Trace as much of the wiring as possible so as to know what is going where in the engine bay and label the wires in English instead of Germ
Check the 2 earth cables from the alternator to the engine block. Find out where the thin earth cable goes

Over winter replace the diodes with a single 3 output Sterling ProSplitR (180amp) along with an intelligent regulator for 3 banks (2xL/A, 1xAGM). Wire the Thruster battery into the mains charger directly instead of routing mains charge through the separate diode from the house battery as it is currently. Fit a battery monitor to the thruster, wire the starter battery into my house monitor and fit an alternator ammeter at the engine controls. Double up or replace any wiring that requires it.

And don't worry I will get this work done by a qualified electrician

Hopefully that should smooth things out and keep us going for a few more years

Thanks to everyone for their input and advice throughout all this and your patience while dealing with Mr Rocksforbrains

Sadly I have to report that we had a week of intermittent battery alarms and voltages reading above 15.2v at the Starter again

In an attempt to overcome this, as the alarm sounding was driving us nuts, I swapped the sense cable from the house battery to the starter battery. This did achieve the desired result but had a side effect of making the engine run like cr*p. This is probably due to the Volvo EVC system but how it knows which battery is being "sensed" is beyond me. So I swapped back to house sensing to keep the engine running smoothly.

It's all very confusing I must admit. So I am going to try to drop in to the dealership this winter and go through the wiring with them to confirm how it's rigged up before I upgrade my system.

I think I have the upgrade sorted. Plan is to fit an Alternator to Battery charger capable of handling 2 inputs (in this case Alternator and Mains). From the 2 outputs I will set up 1 for AGM and connect this to the Thruster then use a modern zero volt drop splitter to the other set up for Sealed Lead Acid for the Starter and House battery. Added to this I think the full remote control monitor would be a valuable option. All cables will be fully checked for size and where required additional cabling will be run and fuses added if required. This will remove the older diode splitters, the funny "house to thruster" loop between the 2 diodes for the mains charging of the thruster and should result in much happier and healthier batteries. Well that's the plan anyway

I'll keep everyone informed as operations proceed and to the eventual results

"voltages reading above 15.2v" combine that with waiting for winter, and you have a concept similar to "unprotected sex".

If you don't know the system, and can't be sure of what's getting what voltage, just remember that for 15.2 to show up anywhere, there's a risk of blowing out all your electronics (typically designed for 13.8 +/- 10% volts, and often using components with only at 15 +/- 10% volt rating) with a slight overload. Along with burning out any filament lamps faster with the increased voltage. And of course, cooking a battery.

I wouldn't call it a crisis, but I wouldn't allow 15+ volts to continue for three or four more months. I know, it's been that way for a while, but the longer it goes, the higher the risk. So far, it hasn't bit you, just been an annoyance. At some point though, it will bite.

I wouldn't call it a crisis, but I wouldn't allow 15+ volts to continue for three or four more months. I know, it's been that way for a while, but the longer it goes, the higher the risk. So far, it hasn't bit you, just been an annoyance. At some point though, it will bite.